Secretary of State John Kerry on Sunday sharply denounced Russian President Vladimir Putin’s “stunning, willful” actions in Crimea, characterizing the move as an “invasion” and saying “all options are on the table” as far as a U.S. response.

“You just don’t in the 21st century behave in 19th-century fashion, by invading another country on completely trumped up pretext,” Kerry said, appearing on CBS’s “Face the Nation.”

Kerry will be in Kiev on Tuesday for talks with members of the new Ukrainian government.

International leaders prepare to ‘isolate’ Russia

In interviews with three U.S. television networks on Sunday, Kerry also said foreign leaders are prepared to put sanctions in place to “isolate Russia economically” if Putin does not roll back his forces in Crimea, an autonomous region of eastern Ukraine with strong loyalty to neighboring Russia. He said options could include visa bans, asset freezes and isolation by the international community on trade and investment, as well as Russia losing its spot in the G8.

“The G8 plus some others and all of them, every single one of them are prepared to go to the hilt in order to isolate Russia with respect to this invasion,” he said on CBS.

Kerry added that there are still plausible alternatives available to Putin, telling ABC that Russia could work toward a diplomatic solution with the U.S. and the United Nations, and could call for observers to be put in Ukraine.

“There are all kinds of alternatives. But Russia has chosen this aggressive act which really puts in question Russia’s role in the world, and Russia’s willingness to be a modern nation and part of the G8,” Kerry said on ABC’s “This Week.”

Kerry said that while the U.S. is keeping its options open, escalated military involvement would “not serve the world well.”

“The last thing anybody wants is a military option in this kind of situation,” Kerry said on NBC’s “Meet the Press.”

Will Putin heed Obama’s warning?

Putin’s military moves in Crimea further stress already weakened ties between the U.S. and Russia.

In a lengthy phone call with Putin over the weekend, Obama condemned the Russian leader’s actions in Crimea, saying that Putin is in violation of international law, according to the White House. The administration announced it would suspend participation in preparatory meetings for the G8 summit that will bring world leaders together in June in Sochi, Russia.

“President Obama wants to emphasize to the Russians that there are a right set of choices that can still be made to address any concerns they have about Crimea, about their citizens, but you don’t choose to invade a country in order to do that,” Kerry said on CBS.

Asked what impact, if any, Obama’s call had on Putin’s mindset going forward in the crisis, the secretary of state said, “We are going to have to wait and see, but I think it was a very important conversation.”

Kerry repeated that Putin’s actions are “unacceptable” and could bring “serious repercussions” if they continue.

He called on Congress to help implement a series of economic sanctions against Russia aimed at helping Ukraine, an idea that has gained traction on both sides of the aisle as a bipartisan group of 12 senators from the Foreign Relations Committee expressed support for U.S. assistance in the crisis.

Partisan split on Obama’s response to Russia

Speaking at the White House on Friday, Obama warned that Russia should not use military force to change the fate of Ukraine, underscoring the need for Ukrainian independence.

Lawmakers were split, unsurprisingly down party lines, on the effectiveness of Obama’s public rebuke of the Russian president.

“I think Putin is playing chess and we’re playing marbles,” House Intelligence Committee Chairman Mike Rogers said on “Fox News Sunday.”

“They’ve really been running circles around us. And I think it’s really the naive position on the National Security Council and the President’s advisers that if we just keep giving things to Russia, they’ll wake up and say, ‘Well, the United States isn’t all that bad.’ That is completely missing the motivations of why Russia does what it does,” the Michigan Republican added.

Sen. Lindsey Graham, a Republican from South Carolina, told CNN’s Candy Crowley on “State of the Union” that Obama needed to offer more than just threats as Putin ramps up military involvement in Crimea.

Democrats quickly rose to Obama’s defense.

Rep. Chris Van Hollen, also appearing in Fox, said that critics should concentrate their attacks on Putin, not Obama.

“We’re 48 hours into an international crisis. I would hope Americans are focused on condemning the actions of Putin rather than in a knee-jerk way again criticizing the President of the United States. Let’s stand together on this,” the Maryland Democrat said.